Brian O’Sullivan is a Professor in the Department of Radiation Oncology at the University of Toronto, Toronto, Ontario, Canada. He also holds the Bartley-Smith/Wharton Distinguished Chair in Radiation Oncology in the Department of Radiation Oncology at the Princess Margaret Cancer Centre, University of Toronto. He is the Head and Neck Oncology Program Chair at Princess Margaret Cancer Centre, the co-Chair of the US NCI Head and Neck Steering Committee, Coordinating Center for Clinical Trials, CTEP, and a full standing member of the Commission of the International Commission on Radiation Units (ICRU). He is the recipient of numerous international awards, and research grants. He has published almost 300 peer reviewed papers, in excess of 50 book chapters, and has written or edited 6 oncology textbooks. His interests include sarcoma and head and neck cancer, translational research, intensity modulated radiotherapy (IMRT) delivery and the principles of image guided radiotherapy, chemo-radiotherapy and molecular targeting. He is a member of the TNM Committee of the Union for International Cancer Control (UICC), Chair of the UICC Prognostic Classification Sub-Committee and represents the UICC as liaison to the American Joint Committee on Cancer (AJCC) in head and neck cancer and bone and soft tissue sarcoma. He is a past President of the Connective Tissue Oncology Society (CTOS), former Head of the Sarcoma Program at the Princess Margaret, and a past Chair of the Sarcoma section for the ASCO Scientific Committee. He has led significant clinical trials in sarcoma management including a landmark paper that compared pre- and post-operative radiotherapy published in the Lancet, and most recently published the first clinical trial addressing the use of IMRT in extremity soft tissue sarcoma. He has published and lectured extensively on sarcoma and will deliver the lecture on radiotherapy for soft tissue sarcoma in the Educational Course in Multidisciplinary Management of soft tissue sarcoma at the ASCO Scientific Meeting in June 2015.